1. Field of the Invention
The present invention relates to a radiation detector, a radiographic imaging device and a radiographic imaging system. In particular, the present invention relates to a radiation detector that accumulates charges generated due to irradiation of radiation, and detects electric signals corresponding to the accumulated charges as data expressing an image. The present invention also relates to a radiographic imaging device that employs the radiation detector for radiographic imaging, and a radiographic imaging system.
2. Description of the Related Art
Radiographic imaging devices for imaging radiographic images are known in which a radiation detector detects radiation that has been irradiated from a radiation irradiation device and passed through an imaging subject. A radiation detector of such a radiographic imaging device is configured with plural pixels disposed in a matrix, each pixel including a sensor portion of, for example, a photoelectric conversion element, that generates charges when irradiated with radiation or when illuminated with light that has been converted from radiation, and a switching element that reads the charges generated in the sensor portion. Such a radiographic imaging device performs radiographic imaging by accumulating charges generated due to irradiated radiation, and detecting (reading) electric signals corresponding to the accumulated charges as data expressing a radiographic image.
As such a radiographic imaging device, there are radiographic imaging devices known that synchronize with a timing of the radiation irradiation from a radiation irradiation device, and for example, a start timing and an end timing for charge accumulation by the radiation detector. As an example of such technology, there is an automated exposure control (referred to below as AEC). In AEC, radiation is detected based on the charges (electric signals) generated in sensor portions due to radiation irradiation, in order to start or stop the accumulation of charges by the radiation detector.
When TFT switches, employed as switching elements for reading charges generated in the sensor portions, are irradiated with X-rays, a leak current occurs. For example, Japanese Patent Application Laid-Open (JP-A) No. 2008-148090 discloses a technology for correcting the leak current that becomes added to image signals, due to the leak current increasing with increasing X-ray irradiation amount.
However, in the technology described in JP-A No. 2008-148090, there are cases in which AEC cannot be performed appropriately by detecting the leak current of the TFT switches for reading image signals to perform radiation detection.